U.S. patent number 6,910,162 [Application Number 10/249,843] was granted by the patent office on 2005-06-21 for memory-module burn-in system with removable pattern-generator boards separated from heat chamber by backplane.
This patent grant is currently assigned to Kingston Technology Corp.. Invention is credited to Ramon S. Co, Tat Leung Lai, David Da-Wei Sun.
United States Patent |
6,910,162 |
Co , et al. |
June 21, 2005 |
Memory-module burn-in system with removable pattern-generator
boards separated from heat chamber by backplane
Abstract
An environmental tester for memory modules has an environmental
chamber for heating the memory modules being tested. One side of
the chamber is a backplane. The memory modules are inserted into
sockets on module motherboards, which are inserted into motherboard
sockets on the backplane. On the other side of the backplane, card
sockets receive pattern-generator cards that are outside the
environmental chamber but electrically connected to the module
motherboards through the backplane. The pattern-generator cards
contain pattern-generators that generate address, data, and control
signals that exercise the memory modules. The pattern-generator
cards can be cooled while the memory modules in the environmental
chamber are heated. Pattern-generator cards can be removed for
repair and module motherboards can be removed for inserting new
memory modules for testing.
Inventors: |
Co; Ramon S. (Trabuco Canyon,
CA), Lai; Tat Leung (Torrance, CA), Sun; David Da-Wei
(Irvine, CA) |
Assignee: |
Kingston Technology Corp.
(Fountain Valley, CA)
|
Family
ID: |
33415574 |
Appl.
No.: |
10/249,843 |
Filed: |
May 12, 2003 |
Current U.S.
Class: |
714/718;
324/750.05; 324/750.14; 324/756.02; 324/762.06; 365/201 |
Current CPC
Class: |
G11C
29/56 (20130101); G11C 29/56004 (20130101); G11C
29/56016 (20130101); G01R 31/2863 (20130101); G01R
31/31905 (20130101); G11C 2029/2602 (20130101) |
Current International
Class: |
G01R
31/28 (20060101); G11C 29/56 (20060101); G01R
31/319 (20060101); G11C 029/00 (); G11C 007/00 ();
G01R 031/02 (); G01R 031/26 () |
Field of
Search: |
;714/718,721,724,725,734,738,742,42,48,49,54,25
;365/200,201,206,211 ;324/760,754,757,763,756 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Tu; Christine T.
Attorney, Agent or Firm: Auvinen; Stuart T.
Claims
What is claimed is:
1. An environmental tester for memory modules comprising: a
backplane forming one side of an environmental chamber; motherboard
sockets mounted on a first side of the backplane; removable module
motherboards for insertion into the motherboard sockets; a
plurality of memory-module sockets mounted on each of the removable
module motherboards, the plurality of memory module sockets for
receiving memory modules for environmental testing in the
environmental tester; card sockets mounted on a second side of the
backplane; removable pattern-generator cards for insertion into the
card sockets; and a pattern-generator on each of the removable
pattern-generator cards for generating address, data, and control
signals to write data to a plurality of memory locations on memory
chips on the memory modules inserted into the memory-module sockets
on the removable module motherboards, whereby memory modules are
tested within the environmental chamber by pattern-generators on
removable pattern-generator cards outside the environmental chamber
that are separated by the backplane that forms one side of the
environmental chamber.
2. The environmental tester of claim 1 wherein the first side of
the backplane is an inner side facing inward into the environmental
chamber and the second side of the backplane is an outer side
facing away from the environmental chamber.
3. The environmental tester of claim 2 wherein the backplane
comprises wiring traces and vias for connecting signals from the
motherboard sockets to corresponding signals from the card
sockets.
4. The environmental tester of claim 3 wherein the backplane
includes a power bus and a ground bus for supplying power and
ground to the removable pattern-generator cards and the removable
module motherboards.
5. The environmental tester of claim 2 wherein the environmental
chamber completely encloses the removable module motherboards when
inserted fully into the motherboard sockets.
6. The environmental tester of claim 5 further comprising: heating
means for heating memory modules inserted into the removable module
motherboards within the environmental chamber.
7. The environmental tester of claim 6 further comprising: cooling
means for cooling the pattern-generator on the removable
pattern-generator cards.
8. The environmental tester of claim 2 wherein the motherboard
sockets are arrayed in rows and columns on the first side of the
backplane; wherein the card sockets are arrayed in rows and columns
on the second side of the backplane.
9. The environmental tester of claim 8 wherein the motherboard
sockets are arrayed in X rows and Y columns on the first side of
the backplane; wherein the card sockets are arrayed in X rows and Y
columns on the second side of the backplane; wherein X and Y are
whole numbers of 2 or more.
10. The environmental tester of claim 9 wherein the backplane
electrically connects signals from a card socket at row I and
column J to a motherboard socket at row I and column J; wherein I
is a whole number from 1 to X and J is a whole number from 1 to Y,
whereby corresponding card and motherboard sockets are connected by
the backplane.
11. The environmental tester of claim 8 wherein the removable
module motherboards are mounted vertically within the environmental
chamber.
12. The environmental tester of claim 11 wherein the removable
pattern-generator cards are mounted vertically outside the
environmental chamber.
13. The environmental tester of claim 2 further comprising:
buffers, coupled to the pattern-generator, for buffering signals
driving the memory modules.
14. The environmental tester of claim 13 wherein the buffers are
mounted on the removable pattern-generator cards.
15. The environmental tester of claim 13 wherein the buffers are
mounted on the removable module motherboards.
16. The environmental tester of claim 2 wherein the plurality of
memory locations includes at least one million unique locations per
memory module.
17. A memory-module burn-in system comprising: a chamber for
heating memory modules; a backplane forming a side of the chamber,
for making electrical connections, the backplane having an inner
side facing into the chamber and an outer side facing away from the
chamber; external connector sockets, on the outer side of the
backplane; internal sockets, on the inner side of the backplane;
wherein each external connector socket is electrically connected to
a corresponding inner socket; pattern-generator cards inserted into
the external connector sockets, for generating test patterns to
write locations in dynamic-random-access memory (DRAM) chips on the
memory modules heated in the chamber; and module motherboards
inserted into the internal sockets, containing memory module
sockets for receiving the memory modules, each module motherboard
being within the chamber and having wiring traces for connecting
signals carrying the test patterns from the pattern-generator cards
passed through the backplane to the internal socket to the memory
modules inserted into the memory module sockets on the module
motherboard; wherein the pattern-generator cards are external to
the chamber but the module motherboards are inside the chamber,
whereby memory modules are heated in the chamber and tested by the
module motherboards using test patterns generated externally by the
pattern-generator cards.
18. The memory-module burn-in system of claim 17 wherein hot air is
blown through the chamber to heat the memory modules inserted into
the module motherboards; wherein cooling air is blown onto the
pattern-generator cards to cool the pattern-generator cards.
19. A burn-in chamber for testing memory modules comprising:
pattern-generator means for generating test patterns for testing
dynamic-random-access memory (DRAM) chips on memory modules; first
socket means for electrically connecting and mechanically
supporting an external card external to a heated portion of the
burn-in chamber; pattern-generator card means for removably
connecting the pattern-generator means to the first socket means;
second socket means for electrically connecting and mechanically
supporting an internal card inside the heated portion of the
burn-in chamber; module motherboard means for removably connecting
to the second socket means; memory module socket means, on the
module motherboard means, for receiving memory modules for testing
on the burn-in chamber; and backplane means for electrically
connecting a first socket means to a second socket means; wherein
the backplane means is further for thermally insulating the module
motherboard means inside the heated portion of the burn-in chamber
from the pattern-generator card means external to the heated
portion of the burn-in chamber, whereby externally generated test
patterns are passed through the backplane means into the heated
portion of the burn-in chamber.
20. The burn-in chamber of claim 19 further comprising: a plurality
of rows and columns of the first socket means and the second socket
means, for receiving pluralities of the pattern-generator card
means and the module motherboard means.
Description
BACKGROUND OF INVENTION
This invention relates to environmental test systems, and more
particularly to memory module burn-in testers.
High-availability and critical systems such as web or transaction
servers required the use of enhanced-reliability components.
Additional testing can be performed on components such as board
assemblies, semiconductor chips, and memory modules. Often this
additional testing is often performed at an elevated temperature.
Thus environmental testing is sometimes known as burn-in.
Weak components often fail earlier at elevated temperatures that at
normal temperatures. Poor solder connections on boards or modules
can break at higher temperatures, and thermal expansion can loosen
poorly seated components. Other manufacturing defects that do not
cause immediate failures can create failures that appear after many
hours of normal operation at normal temperatures, or after just a
few hours at elevated temperatures. Thus elevated-temperature
testing can screen for weak components that might later fail in the
field, enhancing reliability.
Electronic systems such as servers and personal computers (PCs) use
dynamic-random-access memory (DRAM) memory chips mounted on small,
removable memory modules. Older single-inline memory modules
(SIMMs) have been replaced with dual-inline memory modules (DIMMs),
184-pin RIMMs (Rambus inline memory modules) and 184-pin DDR
(double data rate) DIMMs. New kinds of memory modules continue to
be introduced.
The memory-module industry is quite cost sensitive. Testing costs
are significant, especially for higher-density modules.
Specialized, high-speed electronic test equipment is expensive, and
the greater number of memory cells on high-speed memory modules
increases the time spent on the tester, increasing test costs.
Burn-in testing can be quite expensive, as each module may have to
remain at an elevated temperature in a specialized burn-in tester
for many hours or even days. Ideally, the memory module is
exercised electronically during the burn-in testing, rather than
simply be stored at the high temperature and later tested.
Operating the memory module at higher frequencies increases
internal heating within the DRAM chips, providing more realistic
and thorough testing, increasing reliability.
Exercising the memory modules at higher frequencies is difficult,
especially when the modules are within a burn-in oven or heated
test chamber. Cables or wires that connect an external test-pattern
generator or other test equipment to the memory modules within the
oven can be long, severely limiting the frequency of operation.
What is desired is a burn-in test system for testing memory modules
at elevated temperatures. An elevated-temperature memory module
tester is desired that can exercise the memory modules at high
frequencies is desirable. A low cost burn-in tester that can be
easily repaired and updated is desirable.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is an electrical block diagram of a burn-in tester of memory
modules.
FIG. 2 is a side view of a pattern-generator card and a module
motherboard plugged into a portion of the backplane.
FIGS. 3A-B show back and front sides of the burn-in backplane with
pattern-generator cards and module motherboards plugged in.
FIG. 4 is an overhead view of a burn-in tester for memory
modules.
FIG. 5 is a perspective view from the front left of the burn-in
tester.
DETAILED DESCRIPTION
The present invention relates to an improvement in memory-module
testers. The following description is presented to enable one of
ordinary skill in the art to make and use the invention as provided
in the context of a particular application and its requirements.
Various modifications to the preferred embodiment will be apparent
to those with skill in the art, and the general principles defined
herein may be applied to other embodiments. Therefore, the present
invention is not intended to be limited to the particular
embodiments shown and described, but is to be accorded the widest
scope consistent with the principles and novel features herein
disclosed.
FIG. 1 is an electrical block diagram of a burn-in tester of memory
modules. Backplane 28 separates pattern-generator card 44 from
module motherboard 30. A socket (not shown) on the back side of
backplane 28 receives an edge of pattern-generator card 44 while a
socket (not shown) on the front side of backplane 28 receives an
edge of module motherboard 30. Wiring traces and vias on backplane
28 connect signals on the front-side and back-side sockets.
Pattern-generator card 44 contains pattern-generator 42, which can
be a logic chip containing a pattern-generator circuit. A
programmable logic chip such as a field-programmable gate array
(FPGA) may be used for pattern-generator 42. Pattern-generator 42
generates the control, address, and data signals necessary to
exercise memory modules 10 inserted into sockets on module
motherboard 30. Memory cells on memory modules 10 are addressed in
a sequence and written by pattern-generator 42. Pattern-generator
42 can read back the data from the memory cells. The read data can
be compared to expected data by pattern-generator 42, or the read
data can simply be ignored. Failures can be detected later by
external testing once the memory modules are removed from the
burn-in tester.
Buffers 36 provide the necessary drive current to drive the large
input capacitances of memory modules 10. A write signal from
pattern-generator 42 can disable some of buffers 36 (such as data
buffers) during read operations or can be used to reverse
direction.
A clock signal for synchronous DRAMs can also be driven from
pattern-generator 42 or from a zero-delay buffer 36 such as from a
phase-locked loop (PLL). Other specialized clock-driver circuits
can be substituted. Buffers 36 may include registers on some
signals; the registers can be clocked by the clock signal or by
some other signal. Buffers 36 could be located on pattern-generator
card 44 or on module motherboard 30.
Termination is provided by resistors 22, 24. These resistors 22, 24
are useful for reduced DRAMs such as on double-data-rate (DDR)
memory modules. The values of resistors 22, 24 can be chosen to
reduce the voltage swing to half the normal supply-voltage (Vcc)
swing. Expansion is possible by cascading buffers, modules, and
terminations.
FIG. 2 is a side view of a pattern-generator card and a module
motherboard plugged into a portion of the backplane. Card socket 46
receives an edge of pattern-generator card 44 that has contact pads
to make electrical contact in the socket. Signals such as address,
data, and DRAM control are generated by pattern-generator 42 and
buffered by buffers 36 on pattern-generator card 44.
Card socket 46 is mounted to back-side 32 of backplane 28, while
motherboard socket 38 is mounted to front-side 34 of backplane 28.
Metalized vias and traces on backplane 28 connect signals in card
socket 46 to corresponding signals in motherboard socket 38.
An edge of module motherboard 30 contains contact pads that are
inserted into motherboard socket 38. Signals from these contact
pads are routed to memory-module sockets 20 by traces on module
motherboard 30. Memory modules 10 are inserted into memory-module
sockets 20 for burn-in testing. Signals can be routed in parallel
to all memory-module sockets 20, while some signals may be applied
to just one of memory-module sockets 20, or unique address or
socket-select signals can differ among memory-module sockets 20 to
allow one of memory modules 10 to be addressed separately from the
others. When data is not read back for comparison by
pattern-generator 42, then identical, parallel signal connections
can be used for all memory-module sockets 20.
A technician or operator can remove module motherboard 30 using
ejectors 48 to grip module motherboard 30. Once removed, memory
modules 10 can be removed for further testing by another (post
burn-in) tester and new memory modules 10 inserted into
memory-module sockets 20. Module motherboard 30 can then be
re-inserted to burn-in test the new modules.
Pattern-generator card 44 can also be removed from card socket 46
by a technician. This allows for defective pattern-generator cards
44 to be removed for repair while another pattern-generator card 44
is inserted. Different types of pattern-generator card 44 can be
inserted into card socket 46 for testing different types of memory
modules, or for specialized testing.
FIGS. 3A-B show back and front sides of the burn-in backplane with
pattern-generator cards and module motherboards plugged in. In FIG.
3A, back-side 32 of backplane 28 has many card sockets 46 in rows
and columns. Each card socket 46 can receive a pattern-generator
card 44 that contains a pattern-generator 42 that generates control
signals for one module motherboard 30 plugged into the other side
of backplane 28 (FIG. 3B). Wiring traces formed in and on backplane
28 connect electrical signals from one card socket 46 on back-side
32 to one motherboard socket 38 on front-side 34.
In FIG. 3B, front-side 34 of backplane 28 is shown. Rows and
columns of motherboard socket 38 are arrayed on front-side 34. Each
motherboard socket 38 can receive a module motherboard 30. Memory
modules 10 inserted into memory-module sockets 20 are tested by an
opposing pattern-generator card 44 on the opposite side of
backplane 28. Ejectors 48 are useful for removing and inserting
module motherboard 30 into motherboard socket 38 before and after
burn-in testing.
FIG. 4 is an overhead view of a burn-in tester for memory modules.
Memory modules 10 inserted into memory-module sockets 20 on module
motherboards 30 are kept at an elevated temperature by blowing hot
air into a heat chamber surrounding module motherboards 30. This
heat chamber is enclosed by backplane 28 and by sides 86 and top
and bottom dividers (not shown).
Pattern-generator cards 44 are inserted into card sockets 46 on
back-side 32 of backplane 28, and can be kept at a cooler
temperature than module motherboards 30, since pattern-generator
cards 44 are outside of the heat chamber formed by backplane 28 and
sides 86. Backplane 28 provides some insulation between the heat
chamber and pattern-generator cards 44, allowing pattern-generator
42 to be at a lower temperature than memory modules 10.
The front or sides 86 of the heat chamber can be temporarily opened
to allow removal of module motherboards 30 from motherboard sockets
38. Ejectors 48 face the front of the heat chamber, allowing a
technician to pull module motherboard 30 out of motherboard socket
38 through the open front of the heat chamber.
FIG. 5 is a perspective view from the front left of the burn-in
tester. Hot air can be blown into the bottom or sides 86 of the
heat chamber, rising past module motherboards 30 to raise the
temperature of memory modules 10 inserted into memory-module
sockets 20.
Backplane 28 not only provides electrical connection from each
pattern-generator card 44 to each module motherboard 30, but
provides some thermal insulation. Pattern-generator cards 44 are
kept cooler than module motherboards 30 because back area 40 is
separated from the heat chamber of sides 86 by backplane 28.
Cool air can be blown across pattern-generator cards 44 while hot
air is blown through the heat chamber across module motherboards
30. Pattern-generators 42 on pattern-generator cards 44 can be kept
cooler than memory modules 10, allowing for longer life and better
current drive of pattern-generator 42.
Backplane 28, pattern-generator cards 44, and module motherboards
30 can be mounted on a rack that is enclosed by sides 86. Several
racks can be mounted on top of each other, or beside one another in
a larger burn-in unit enclosure. Hot air can be blown in from the
bottom or sides of the unit. Local heaters, thermocouples, or other
temperature-sensors can also be used to better regulate and control
heating. The unit could be turned, rotated, flipped, or otherwise
re-oriented. Cooling, humidity, or other environmental testing
could also be performed.
Backplane 28 can route power and ground to all pattern-generator
cards 44 and all module motherboards 30. Monitoring and control
signals can also be routed through backplane 28, such as reset
signals to pattern-generators 42 or result or status data from
pattern-generator 42 to a central controller or network interface
to a host.
Alternate Embodiments
Several other embodiments are contemplated by the inventors. All
memory modules designated as high reliability can be tested within
the burn-in system for various periods of time, or only a sampling
of memory modules from production runs can be tested within the
burn-in chamber to monitor reliability and detect manufacturing
problems. Prototype and engineering testing can also be performed.
Other testing of the memory modules can also be performed before or
after testing within the burn-in system.
Pattern-generator 42 could use a standard DRAM controller activated
by a programmable device such as a processor or state machine, or
pattern-generator 42 could be a state machine or controller.
Buffers could be located on pattern-generator card 44 in the cooler
environment, or could be located on module motherboard 30 in the
hot environment, but closer to the memory modules being driven.
Some buffers, registers, or clock drivers could be on
pattern-generator card 44 while others are on module motherboard 30
or even on backplane 28. Patterns could be generated to write all
locations on large DRAM chips, such as by writing to a million or
more addresses.
Rather than have each module motherboard 30 driven by one
pattern-generator card 44, a pattern-generator card 44 could drive
several module motherboards 30.
The number of test sockets on the motherboards could vary, and
additional components could be added to the module motherboards.
More than one edge socket could be used for each connection.
Different mounting mechanisms and electrical connections could be
substituted. The motherboard and pattern-generator card may be
substantially perpendicular to the backplane by being at an angle
such as from 60 to 120 degrees rather than exactly 90 degrees.
A thicker fiberglass board or other additional insulation that
better insulates the pattern-generator cards from the elevated
temperatures near module motherboards can also be used.
Many kinds of memory modules can be tested. Modules using standard
DRAM or newer EDO and synchronous DRAM can be tested. The system is
ideally suited for testing the highest-speed memory modules, since
signal trace length and capacitive loading is minimized. Other
memories such as RAMBUS modules, DDR modules, and PC133 synchronous
modules can be tested.
Various sizes of memory in the memory module, and form factors for
memory modules can be used with the invention, limited by the
module motherboard 30 and memory-module sockets 20. Different kinds
of module motherboards and pattern-generator cards can be
substituted.
A Yamaichi type connector could be used as the memory-module
sockets, but a production-quality connector/socket with low
insertion force may be substituted. A production quality
connector/socket can take more insertions (greater than 100,000
times) than conventional sockets on motherboards (rated for 100
insertions). A production socket also has an ejector normally
located at the 2 edges of the socket. This alleviates the ejection
of modules.
A network controller card on the ISA or PCI bus that communicates
with a main system interface or host can be used. A controller card
or a standard parallel or serial-port may interface to the main
system interface or host. FireWire, USB, or other emerging
standards can be used for the interfaces.
Cascading or expansion is possible. Capacitive loading by the
memory modules can limit the number of modules that can be placed
on a bus for a given operating frequency. In order to use one
pattern generator card, another buffer can be placed at the end of
the bus for regenerating the test signal. The regenerated test
signal is used to drive a subsequent bank of modules and
terminations. This is possible when all the test signals are
propagating in the same direction, for example, writes to the
modules only.
During writes, all memory modules can be selected and written in
parallel at the same time. There can be separate module select
lines (static, not dynamic) for each module. Writing can happen
concurrently on all modules. During read, only one module is
selected, and a bus conflict is avoided. The read data can be read
back or ignored. The address, data, and most control lines are
bussed in parallel; the module select lines are not. The module
select lines are DRAM chip selects which are made available as pins
on the memory module for the module select function.
The abstract of the disclosure is provided to comply with the rules
requiring an abstract, which will allow a searcher to quickly
ascertain the subject matter of the technical disclosure of any
patent issued from this disclosure. It is submitted with the
understanding that it will not be used to interpret or limit the
scope or meaning of the claims. 37 C.F.R. A.sctn.1.72(b). Any
advantages and benefits described may not apply to all embodiments
of the invention. When the word "means" is recited in a claim
element, Applicant intends for the claim element to fall under 35
USC A.sctn. 112, paragraph 6. Often a label of one or more words
precedes the word "means". The word or words preceding the word
"means" is a label intended to ease referencing of claims elements
and is not intended to convey a structural limitation. Such
means-plus-function claims are intended to cover not only the
structures described herein for performing the function and their
structural equivalents, but also equivalent structures. For
example, although a nail and a screw have different structures,
they are equivalent structures since they both perform the function
of fastening. Claims that do not use the word means are not
intended to fall under 35 USC A.sctn. 112, paragraph 6. Signals are
typically electronic signals, but may be optical signals such as
can be carried over a fiber optic line.
The foregoing description of the embodiments of the invention has
been presented for the purposes of illustration and description. It
is not intended to be exhaustive or to limit the invention to the
precise form disclosed. Many modifications and variations are
possible in light of the above teaching. It is intended that the
scope of the invention be limited not by this detailed description,
but rather by the claims appended hereto.
* * * * *